In a lead generation program, I have a trigger campaign that sends an initial follow up email after a form is submitted. I am trying to set up an second trigger campaign that will send that same follow up email with a new subject line to those leads that did not open the initial follow up email. I would like the timing for the second send to be exactly 4 days after the 1st initial email was sent (and not opened). Using the date of activity constraint on the "was delivered email" filter and choosing "in past - 4 days" seems to give me any lead that has not open the email within the past 4 days, which isn't what I'm looking for. (I've attached the smart list I built for reference). I know I can select the calendar day that was exactly 4 days ago, but I don't want to have to manually change that date every day in order for the filter to work properly. Does anyone have a solution? Suggestion? Any insight would be appreciated. Thank you!